One could simply dry e.g. fresh broccoli by lyophilisation without prior heat treatment to obtain a dried broccoli. Such dried broccoli has an unacceptable short life because it would still contain relatively high levels of enzymes. Such products are unsuitable for use in food industry as mass produced food products need to have a long shelf life. The prior art discloses various examples of dried broccoli. High amounts of salt, sugar, glycerol, sorbitol, however, severely limit the application as the dried product inherently tastes very sweet or very salty and has lost the “bite”. Relatively high amounts of water are undesirable as the water may migrate to other components in the dried food product and cause it stick together like in dried soups.
One example of a very sweet dried vegetable and a process for producing the same is disclosed in U.S. Pat. No. 4,832,969. In example 7 thereof, a process is disclosed for producing dried broccoli florets comprising heating the florets in distilled water containing 0.06 wt % of MgCO3 at 212 degrees F. (=100 degrees C.) for 70 seconds. The vegetable solids content of a dehydrated material prepared according to description is only 28 wt % for broccoli florets. The dried vegetable product comprises typically more than 40% of glycerol and sugar resulting in a very sweet product with limited application. In fact, the product is so sweet it is recommended to add a bittering agent like potassium chloride to moderate the sweet taste.
GB-2 114 865 discloses a process to prepare dried vegetables. However, all examples show that the resultant dried vegetable contains more than 50 wt % of additives such as NaCl, monosodium glutamate (MSG), proteins or sugars and thus relatively low amounts of vegetable solids. The resultant products have a limited application due to the high levels of additives and sweet/salty/umami taste. Moreover the dried vegetables prepared according GB-2 114 865 are chewy and do not have a good “bite”.
F. S. Jayaraman et al. (International Journal of Food Science and Technology (1990) 25, 47-60) discloses a process for drying cauliflower whereby cauliflower is incubated in a solution comprising 3 wt % NaCl and 6 wt % of sucrose for 12-16 hrs at 0-4 C. Jayaraman et al explicitly teaches that more than 3 wt % of NaCl does not provide added benefits. However, this process results in a dried vegetable with a sugar content of 39 wt %, NaCl content of 16 wt % and less than 40 wt % vegetable solids. Again the high levels of salt and sugar limit the application of such products. Perhaps more importantly, the long soak causes important nutrients like vitamin C to leach out of the vegetable: only 14% of the vitamin C remained in the dried vegetable. The bite is not good but chewy.
It is an object of the invention to provide a process to prepare a dried vegetable product with the following features: a high content of vegetable solids, substantially free from polyols such as sorbitol or glycerol, having a good bite after re-hydration (not chewy), a relatively neutral taste such that it can be used in a wide variety of dry applications, a low water activity while maintaining good re-hydrating properties and good light stability, suitable to be packaged with other dried ingredients without undesirable migration of water from the dried vegetable products, and a high retention of vitamin C. Another object of the invention is to provide a dried vegetable product for use in mass produced food products with long shelf life.